L3 Mills - Form and Function in Placentals 1 - teeth, jaws and gut

Question 1

Name and describe the 4 parts of a tooth

Answer 1

Starting from the inside:

1. Pulp - vascular/nervous supply to the tooth
2. Dentine - more mineral/less organic than bone
3. Prismatic enamel (CaPO4) - strong and aids in grinding up differnet materials

Question 2

What holds a tooth in place?

Answer 2

Gum and cement (bone)

Question 3

What is Heterodonty specialised for?

Answer 3

1. Harvesting (cropping and tearing) - incisors and canines

2. Processing (crushing and shearing) - premolars and molars

Question 4

What is the dental formula?

Answer 4

(i x c x pm x m) x 4

Question 5

For the Bunodont tooth:

a) what kind of animals have these
b) what are the characteristics and uses

Answer 5

a) fruit bat, bears, pigs, humans

b) flattened for crushing in omnivores

Question 6

For the Lophodont tooth:

a) what kind of animals have these
b) what are the characteristics and uses

Answer 6

a) rhinoceros

b) ridged grinding surfaces - more dentine is exposed, ideal for grazing and grinding plant cells

Question 7

For the Hypselodont tooth:

a) what kind of animals have these
b) what are the characteristics and uses

Answer 7

a) beavers
b) open rooted for continuous growth, enamel on the front and dentine on the back, creates a sharp tooth

self sharpening as continually growing and top and bottom wear on each other

Question 8

How are hypsodont teeth viewed as an evolutionary arms race?

Answer 8

They are seen as an EAR against grasses that deposited more and more silica in their cell walls as an anti herbivore defence.

Question 9

What kind of animal has hypsodont teeth?

Answer 9

Horses - they are flat deep rooted teeth

Question 10

Describe the shape and structure of Selenodonts?

Answer 10

• crescent shaped molars
• convergent with hypsodonty in functional anatomy
• there is a gap between incisors and molars allowing teeth to have different functions

Question 11

What is the gap between teeth types in horses called?

Answer 11

Diasmor

Question 12

What kind of diet do animals with sectorial cheek teeth have?

Answer 12

carnivorous diet

Question 13

Why are sectorial cheek teeth associated with tight jaw articulation and a change in head shape?

Answer 13

Head shape change i for supporting muscles needed for a strong bite

Seen in cats and dogs

Question 14

What kind of dentition/jaw do fallow deer have?

Answer 14

Complete loss of upper incisors, replaced by a horny pad

Question 15

What kind of animals have filtering teeth and what is their function?

Answer 15

Certain seals such as leopard and crabeater seals and baleen whales have these filter teeth to push water out once having taken in a mouth full of krill

Question 16

Name the 4 chambers of the stomach in foregut fermenters

Answer 16

1st rumen - re chew and reprocess their food

Reticulum - ferments the plant material

Masum

Abomasum - acid stomach

Question 17

What effect do tannins have on the system?

Answer 17

They slow down an already slow system

Question 18

Describe the stomach of a hind gut fermenter

Answer 18

• Enlarged caecum - where digestion takes place
• chew food more
• periodically emptied caecum
• faster caecum

Question 19

What animals have:

a) a hind gut fermenter
b) a fore gut fermenter

Answer 19

a) horses, deer, voles, some old world monkeys

b) cows

Question 20

What is coprophagy and which animals do it?

Answer 20

Eat your own poo - rabbits

Question 21

What is an animals home range?

Answer 21

a home range is where an animal goes around its daily routine, forages etc.

Question 22

Why is a carnivores home range larger than a herbivores?

Answer 22

An elk will need 100ectres but a bear will need 1000hhectres to maintain its energy requirement

This is because grasses and plants are easier to come by than the diet of a bear to find berries or prey